[aspectc-user] LNK2005 with woven Codes
Yan Mao
maoyan at gmx.net
Mon Oct 30 10:11:30 CET 2006
Hello Olaf,
sorry to bother you again, but I tested this inline function, it seems to work correctly.
I define this global_counter function in a header file, and call it in a class memeber function and main method, and I get the correct answer, that the counter increments by each call.
can you give some other tips?
thanks,
Yan
-------- Original-Nachricht --------
Datum: Fri, 27 Oct 2006 10:41:50 +0200
Von: Olaf Spinczyk <Olaf.Spinczyk at informatik.uni-erlangen.de>
An: Yan Mao <maoyan at gmx.net>
Betreff: Re: [aspectc-user] LNK2005 with woven Codes
> Hello Yan,
>
> let me explain COMDAT support with a simple code example:
>
> inline int global_counter () {
> static int c = 0;
> return c++;
> }
>
> If this inline function is define in a *header* file, the compiler and
> linker have a problem, because the code is "seen" by the compiler in
> more than one translation unit. In this particular example this is no
> problem with the code for the function as it is inlined anyway. However,
> the function contains a static local variable, which means that some
> global storage has to be allocated. Although compiled in more than one
> translation unit, the compiler and linker have to make sure that this
> global storage is allocated only once! This is COMDAT support.
>
> Normally it is implemented by a concept known as "vague linkage", i.e.
> symbols in different translation units marked as "vague" (or "link
> once") are regarded as *one* by the linker if they have the same name
> and size.
>
> AspectC++ relies on this compiler/linker feature. This is normally no
> problem, but with your special build environment ...
>
> Maybe you could check this with the simple example shown above.
>
> Best regards,
>
> Olaf
>
>
> Yan Mao wrote:
> > Hallo Olaf,
> >
> > I did some experiments and I am now almost sure that, my tool works
> different as VS Tool.
> >
> > I tested the same woven codes with both VS Tool and my special Tool,
> they gave me too difference results. With My tool, Aspects are instantiated
> twice, but with VS Tool only once.
> >
> > I posted the woven codes and different results, please take a look, and
> maybe you can give me some advice, how to avoid the problem.
> >
> > And what is "COMDAT-support", how can I make sure, that if my tool has
> "COMDAT-support" or not?
> >
> > Thanks,
> >
> > Yan
> >
> > p.s. Because both English and German are not my mother language, and I
> am not sure that my German is much better than my English, so i still use
> English.
> >
> >
> >
> > -------- Original-Nachricht --------
> > Datum: Tue, 24 Oct 2006 05:08:12 +0200
> > Von: Olaf Spinczyk <Olaf.Spinczyk at informatik.uni-erlangen.de>
> > An: Yan Mao <maoyan at gmx.net>
> > Betreff: Re: [aspectc-user] LNK2005 with woven Codes
> >
> >> Hello Yan,
> >>
> >> to be honest, your description of the problem is not very precise and I
> >> have no chance to reproduce the misbehavior.
> >>
> >> If both advices are defined in the same aspect and if you don't define
> >> your own aspect instantiation strategy with "aspectof()", I don't see a
> >> reason why there should be two aspect instances. Or do you use some
> >> special linker that has no "COMDAT-support"? Could you send me more
> >> information about your build environment? If it helps, you could also
> >> write in german.
> >>
> >> - Olaf
> >>
> >> Yan Mao wrote:
> >>> Hallo Olaf,
> >>>
> >>> thanks for the answer. I changed my codes, and they worked now well.
> >>>
> >>> But as I tried to use the same aspect in another project, I got
> another
> >> problem.
> >>>
> >>> In my aspect,I want to break an action, if the execution time expands.
> >>>
> >>> In an advice of one pointcut I set the "start time", and in the other
> >> advice of another pointcut, i'd like to read the "start time", so that
> i can
> >> compare the "current time" with the "start time".
> >>> But unfortunately, i cant get the setted start time.
> >>>
> >>> It seemes that, 2 Aspect object are created in der Laufzeit, where
> only
> >> one object should be created. That's why I cant get the set value.
> >>> Actually the AC woven codes are almost the same with the sample
> project,
> >> which worked well. But They just don't work!
> >>> To notice, that my current project are build on a system, which wraps
> >> the Visual Studio APIs and Libraries, and offers its own APIs. And I
> must
> >> also use its own Compiler to compile and link the projects, which
> should call
> >> VS compiler cl.exe internally.
> >>> I suppose that it has somthing to with the compiler, but i dont know
> how
> >> to get the wright way to solve the problem.
> >>> Can you give me some tipps?
> >>> Sorry for my poor English, if it is hard to read. But I really need
> >> help!
> >>> Thanks in advance,
> >>> Yan
> >>>
> >>>
> >>>
> >>> -------- Original-Nachricht --------
> >>> Datum: Sun, 22 Oct 2006 08:20:11 +0200
> >>> Von: Olaf Spinczyk <Olaf.Spinczyk at informatik.uni-erlangen.de>
> >>> An: Yan Mao <maoyan at gmx.net>
> >>> Betreff: Re: [aspectc-user] LNK2005 with woven Codes
> >>>
> >>>
> >>>> Hello Yan,
> >>>>
> >>>> it looks as if you defined the member functions of "Profiling" as
> >>>> non-inline functions in the aspect header file. If the aspect affects
> >>>> more than one translation unit, the code will be generated more than
> >>>> once and the linker complains. Better define the small functions as
> >>>> inline functions.
> >>>>
> >>>> Best regards,
> >>>>
> >>>> Olaf
> >>>>
> >>>> Yan Mao wrote:
> >>>>
> >>>>> Hello,
> >>>>>
> >>>>> I got LNK2005 errors by linking the woven codes.
> >>>>> it seems to me, that the same aspect is expanded in multiple cpp
> >> files.
> >>>>> I have #ifndef #define and #endif macros in every head file, and I
> >> also
> >>>>>
> >>>> notice that AC++ compiler generate constant names such as
> >>>>
> >>>>> __ac_have_C__DA_ACSTUTest_aspects_Profiling_ah__
> >>>>> __ac_need_C__DA_ACSTUTest_aspects_Profiling_ah__
> >>>>>
> >>>>> But they still dont work. What's wrong with my codes?
> >>>>>
> >>>>> I'd like to post the sample codes, hope anyone can help me!
> >>>>>
> >>>>> thanks in advance!!
> >>>>>
> >>>>> Yan
> >>>>>
> >>>>>
> >>>
> >
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